The number of syphilis cases in New York City jumped 55% in 2002 from the previous year, with the increase concentrated among gay and bisexual men, health authorities announced Thursday. After a decade when the number of cases of the disease dropped steadily, the number of syphilis cases began rising in 2001.

"This is a very troubling multicity outbreak that is almost exclusive among men who have sex with men," said New York City health commissioner Thomas Frieden.

Preliminary figures indicate there were 436 new cases of the disease in New York City in 2002, compared with 282 in 2001. In 2000 there were just 117 new cases of syphilis reported. Los Angeles, Miami, Chicago, San Francisco, Minneapolis, and Houston have also experienced rising rates of syphilis in the past two years, with the increases attributed largely to rising infection rates among gay and bisexual men.